Objectives: Economic hardship has a serious impact on adolescents’ mental health. The financial impact of the coronavirus disease 2019 (COVID-19) pandemic was more severe for low-income families, and this also impacted adolescents. This study aimed to examine the associations of economic deterioration (ED) caused by the COVID-19 pandemic and low socioeconomic status (SES) with adolescents’ suicidal behaviors.Methods: This study analyzed data from the 2020 Korea Youth Risk Behavior Web-based Survey, which included 54 948 middle and high school students. Odds ratios (ORs) of suicidal ideation, suicidal planning, and suicide attempts related to ED and SES were calculated using multivariable logistic regression. We calculated relative excess risks due to interaction to assess additive interactions.Results: The ORs for suicidal ideation, suicidal planning, and suicide attempts related to combined severe ED and low SES were 3.64 (95% confidence interval [CI], 3.13 to 4.23), 3.88 (95% CI, 3.09 to 4.88), and 4.27 (95% CI, 3.21 to 5.69), respectively.Conclusions: ED and low SES were significantly associated with suicidal behaviors in adolescents. Although no significant additive interaction was found, the ORs related to suicidal ideation, suicidal planning, and suicide attempts were highest among adolescents from low-income families with severe ED. Special attention is needed for this group, considering the increased impact of economic inequality due to the COVID-19 pandemic.

Objectives: Korea and Japan have managed the spread of coronavirus disease 2019 (COVID-19) using markedly different policies, referred to as the “3T” and “3C” strategies, respectively. This study examined these differences to assess the roles of active testing and contact tracing as non-pharmaceutical interventions (NPIs). We compared the proportion of unlinked cases (UCs) and test positivity rate (TPR) as indicators of tracing and testing capacities.Methods: We outlined the evolution of NPI policies and investigated temporal trends in their correlations with UCs, confirmed cases, and TPR prior to the Omicron peak. Spearman correlation coefficients were reported between the proportion of UCs, confirmed cases, and TPR. The Fisher <i>r</i>-to-<i>z</i> transformation was employed to examine the significance of differences between correlation coefficients.Results: The proportion of UCs was significantly correlated with confirmed cases (<i>r</i>=0.995, <i>p</i><0.001) and TPR (<i>r</i>=0.659, <i>p</i><0.001) in Korea and with confirmed cases (<i>r</i>=0.437, <i>p</i><0.001) and TPR (<i>r</i>=0.429, <i>p</i><0.001) in Japan. The Fisher <i>r</i>-to-<i>z</i> test revealed significant differences in correlation coefficients between the proportion of UCs and confirmed cases (<i>z</i>=16.07, <i>p</i><0.001) and between the proportion of UCs and TPR (<i>z</i>=2.12, <i>p</i>=0.034) in Korea and Japan.Conclusions: Higher UCs were associated with increases in confirmed cases and TPR, indicating the importance of combining testing and contact tracing in controlling COVID-19. The implementation of stricter policies led to stronger correlations between these indicators. The proportion of UCs and TPR effectively indicated the effectiveness of NPIs. If the proportion of UCs shows an upward trend, more testing and contact tracing may be required.